1985 VRO running rough video

[DeclansDaddy]

Here's a link to my video. http://youtu.be/7NSecJ3Hl-c

I got this motor after it sat a while winterized. I rebuilt the carbs, new plugs and wires, had to put a power pack on it, disassembled and cleaned up the timing base, decarbed the motor with the Dunks method and this is what I'm getting. It runs rougher at idle. In the video the motor fluctuates between 1000-2200 rpm and I'm not touching the throttle. It's seems to be missing and maybe even lean sneezing but I don't know of any way to richen the fuel mixture on these carbs. Also I deleted the VRO and am mixing OMC oil 50:1. Any ideas?

 

[racerone]

As is always suggested, you need to start with a compression test ?---These motors are famous for broken piston rings.---No amount of tuning / adjusting will fix that.

 

[Bosunsmate]

how do your plugs look?

 

[rothfm]

Agreed, Start with compression. If good its worth running thru a Link-Sync procedure. Idling at 2k is high and something is out of spec. If all that is good, I usually find Lean sneeze to be carbs and fuel delivery.

 

[DeclansDaddy]

Sorry forgot to mention we did a comp. test and all cylinders were 85-100lbs which I was told by a mechanic in town that that's not too bad for that year and model. Plugs look clean still. Not soaked or anything. I know my best bet is to take it to someone qualified to mess with it but I just was thinking maybe it was an easy fix.

 

[racerone]

Next step is to remove the 3 small bypass covers on each side of the block.---Inspect pistons and rings there.--Might cost you some cheap gaskets.---------Compression of 85 psi indicates problems !!!

 

[Bosunsmate]

You could try putting a couple of fingers in the carbs in turn and seeing if that smoothes it out, if it does then that carb is therefore lean/blocked up.
Otherwise i suggest removing the bypass gaskets as mentioned above

 

[DeclansDaddy]

Well I went back out today and ran it some more and it would run great for about 30 seconds then start sputtering again then clear up again. I think I'm going to take it to a shop and have them see what they can do. I really just need to know if the motor is worth keeping or am I just going to have more trouble then it's worth and I should be on the lookout for a replacement motor. Guess I'll see what happens.

 

[emdsapmgr]

Would be good to confirm the compression numbers with a second gauge. Compression numbers should be within 10% of each other, and yours may be slightly out of that tolerance. Best to validate the numbers for sure before you put one more $ into it. Agree with roth. That engine should idle on the trailer about 1200 rpm's. Yours is high at 2000 and is varying too much. Could need a "sync and link" and possible carb overhauls-specifically the idle passages in the upper carb body. [If one of the carbs (main butterfly) is not fully closed at idle, it can fluctuate rpm's while idling.]

 

[racerone]

Post # 1 says that carburetors gave been rebuilt already.

 

[DeclansDaddy]

I'm sorry I may of mislead you. In the video I had the throttle up a little. The motor does idle much lower however it runs so rough it wants to conk out so I had to give her some throttle to keep it running. I'll try to get my hands on another compression gauge just for sure but I've never had any problems with mine. It's a pretty high dollar Snappy gauge. The mechanic I talked to told me he cut his teeth on these motors in the 80's and they were always low compression motors so he told me anything over 85 shouldn't give me problems but yes the 15 psi difference might be a problem. When I say the carbs were rebuilt I mean they were taken apart and cleaned by me. They were actually spotless on the inside but I went ahead and sprayed gumout and air through everything. But I don't have much faith in my marine abilities so I may have missed something.

 

[emdsapmgr]

When this engine idles, the carb butterflys are completely closed. All air goes thru the small holes in the butterfly plates. The fuel enters thru the idle passages. If these get at all plugged, it will run lean at idle and miss, called a "lean sneeze". If you slightly open the throttle plates, just a little, that permits the mid jets to contribute fuel and it will idle smoother, as your engine shows in the video. The way I clean the carbs is to spray one passage of one carb with a gumout type aerosol spray. Observe the spray coming out of the other end of that hole. Then pick up carb #2 and do the exact same passage and note the spray coming out the end of that carb passage. The exiting spray must be identical, or you have a restriction. Repeat by doing one passage at a time on each carb, comparing as you go. You may find one restricted. Also, be sure you pull all the idle jets out and visually inspect them.

 

[DeclansDaddy]

Yea I'm thinking the carbs may need to be done by a more qualified person. I watched a video today on it and the guy removed little expansion type plugs from the carb and discarded them. Cleaned out those holes and put new plugs in. I did not do this. I'm not sure what those passeges are for but he made it clear not to skip that step. I think I'm going to double check the compression and if that comes out acceptable then I'm going to pull the carbs off and take them to a shop and have them go through them. If that doesn't fix my problem then I guess I'll take the whole works to a shop and pay for an opinion. I'd love to repower with a brand new motor but it's just not in the cards right now.

 

[racerone]

If you are capable of doing the carburetor work then you are capable of doing the piston inspection.------Take those bypass covers off !-------There may not be anything wrong and it will cost you just pennies for new gaskets.--------If you take the carburetors to a big shop it will cost you some coins . What if that does not fix it ?????

 

[Bosunsmate]

Dont take it to a shop unless you have money to burn.
All you do on the carb is blow something through every hole and make sure it comes out another hole.
You dont need to discard any of those jets

 

[DeclansDaddy]

It wasn't jets. I took the jets out and all. They look like little freeze plugs and to get them out you have to punch thought them with an awl and pop them out. I see re rebuild kits come with new ones. Now I've read on a couple forums to not skip removing them and cleaning them out also. I can order the kits and do the carbs myself, I have mech. abilities just not to much on boats. I'll pop the covers off that you speak of soon as I can figure out what you're talking about. Been raining here today so I didn't get to mess with it. I did use a bore scope with a HD screen on it and look in all the cylinder and I didn't see anything odd. There was no scarring on the walls and actually I could see good x-hatching. The motor was suposively rebuilt with new bearings and rings with only a few hours put on it and the transom on the boat started cracking and from the cross hatching I seen then I'd believe it but I guess if I can pull the covers and see if maybe the rings are stuck that'd be a good thing to check off the list.

 

[Bosunsmate]

It wasn't jets. I took the jets out and all. They look like little freeze plugs and to get them out you have to punch thought them with an awl and pop them out.

No no no, jets are screwed in and out with a flat head, and very carefully, the freeze plugs are something totally different

 

[DeclansDaddy]

No no no, jets are screwed in and out with a flat head, and very carefully, the freeze plugs are something totally different

Yea that's what I'm saying. I pulled the jets out and cleaned them and their passages and reinstalled them. I know not to scar jets, I race dirt cars and jet changes are regular. I saw the "freezeplugs" when I had it apart but didn't think anything about them. Now I'm learning they should be removed and cleaned out also.

 

[Bosunsmate]

Well id take it to the water and see how it runs or pop those bypass gaskets off

 

[emdsapmgr]

I try not to remove the core plugs on the carb bodies. Spraying some aerosol Gumout thru the carb passages should be enough to clean them. It's worked for me. If you do remove them and replace them with the plugs from a new carb kit, you will have to reseal them as you install them. You'll need some special gas-resistant sealant, called Gasoila-in order to make sure the core plugs don't leak upon reassembly.